1. Field of the Invention
The present invention relates to an electric guitar pick-up system, and more particularly to a detachable electric guitar pickup system that provides a musician an easy way to change pick-up systems on his/her electric guitar.
2. Description of the Prior Art
This invention relates broadly to electrical musical instruments of the string type. It is typically applicable to an electrical guitar or bass guitar or similar musical instrument having a plurality of stretched strings extending across a body and a neck, between the head of the instrument and a bridge assembly connected to the body, in which the strings are caused to vibrate by plucking or picking same.
In order to derive an output from such an electrical guitar, bass guitar or other similar electrical musical instrument, the instrument is conventionally provided with an electromagnetic pick-up comprising a number of magnetic elements (pole pieces) having wound there around a conductive coil. Typically, one such magnetic element is disposed directly beneath each string of the instrument. The strings are constructed of a magnetizable substance, such as steel, and, therefore, become part of the conductive path for the magnetic lines of flux of the pole pieces. Accordingly, when any of the strings are caused to vibrate this causes a disturbance in the magnetic field of the associated pole piece. This has the effect of generating a voltage in the conductive coil which voltage may be suitably amplified and transmitted to a loudspeaker system.
The current state of the art has many different designs for electric guitar pick-up systems. Each of the designs of the current state of the art claim certain advantages. Schaller Pat. No. 4,580,481 describes a pick-up for a guitar having a coil which is provided with two magnets that can be individually changed in position such that the magnetic field of each magnet is restricted to a group of only three strings thus changing the position of a magnet will only affect the signal of one group of strings in volume or phase, so that for instance the sound volumes of the two groups of strings can be brought into any desired balance. Another Schaller invention Pat. No. 4,535,668 has as its specific object to provide a pick-up whereby the strength and phase of the output signal produced by the vibration of each string of the instrument with which it is used may be individually adjusted by hand in a simple manner without the need for special tools. Duncan Pat. No. 4,524,667 discloses a pick-up system having a coil stack assembly in which coils are combined with permanent magnet members and stacked one on top of the other. An advantage of the Duncan design is that by selectively varying the geometrical dimensions of the permanent magnet material, the pole piece and the air gap, a wide range of output sounds can be obtained. Another advantage is that the stacked coils which are wound in separate directions eliminate the pick-up of a 60 cycle hum.
Fender Pat. No. 4,463,648 describes a pick-up which provides better separation between the sound from each string and a humbucking pick-up. The humbucking pick-up is designed to reject magnetic fields from lighting fixtures, motors, transformers and the like, which are sources of 60 hertz noise and would cause 60 cycle hum to be picked up by the pick-up and amplified through a loudspeaker system, manifesting an objectionable hum. The humbucking pick-up overcomes this problem by including a pair of identical pick-up assemblies each having a plurality of magnetic pole pieces and a coil, pick-up assemblies being positioned in parallel, spaced, closely adjacent relationship. The coils of the two pick-up assemblies are run in opposite directions and the two coils are connected either in series or in parallel. Because the direction of current flow in each coil is governed by the magnetic polarity, the direction of current from one coil is opposite to that of the other coil for each string. However, since the directions of the windings of the two coils are opposite the signals induced in the coils as a result of string vibrations are additive and the output signal is the sum of the signals induced in each coil. All of the pole pieces of one of the pick-up assemblies have their North poles adjacent to the strings and their South poles relatively remote from the strings whereas all of the pole pieces of the other pick-up assembly have their South poles adjacent to the strings and the North poles relatively remote from the strings. Signals from external sources such 60 cycle power hum are independent of the magnetic polarity and accordingly, such power line sources produce voltage that are in phase. However since the coils are wound in opposite directions, these in phase signals cancel and the output signal is the difference between the powerline signals induced in each coil. This means that any noise from power sources which is only manifested as an objectionable hum, is effectively reduced or cancelled. The Pat. No. 4,463,648 improves upon the humbucking pick-up by mounting the pick-up on the body of an electrical instrument at an obtuse angle relative to the direction of the strings, the angle of mounting of the housing being a direct function of the longitudinal offset whereby each of the pick-up assemblies is centered under the strings. This improves the harmonic content and thereby the sound produced by the pick-up.
DiMarzio Pat. No. 4,442,749 describes an electrical pick-up comprising a pair of superimposed co-axial bobbins, each axial wound with a coil having its axis perpendicular to the stringed instrument strings, an integral plate of magnetic material comprising a base disposed between the two bobbins perpendicular to the coil axis and two side walls extending upwardly and perpendicularly from a base to at least immediately below the top base of the upper bottom and a plurality of rod-like permanent magnets extending through at least the upper coil parallel to the axis thereof and in contact with the base of the integral plate and wherein the magnets have like pluralities at the tops thereof. Again this double coil design is such that externally generated hum will be eliminated. The DiMarzio design claims to produce a strong signal while at the same time eliminating the hum of 60 cycles. DiMarzio also claims that humbucking pick-ups such as the Fender design described above causes string vibrations to be sensed over a relatively broad length of string, that results in cancellation of various frequencies, due to the spacing of the coils under the strings. The DiMarzio design claims to eliminate this problem.
Aaroe Pat. No. 4,372,186 is another design of a humbucking electromagnetic pick-up. The Aaroe pick-up employs a single coil wound in two oppositely wound and concentric sections. The key advantage of the Aaroe design is that the concentric coils are very closely spaced. This helps to eliminate any imbalance between the two side legs of one coil, or the output of the conventional humbucking configuration of two coils wound in opposition which could result from an interfering radiation that is not at a point substantially normal to the plane of the instrument strings above the coils.
Armstrong Pat. No. 4,283,982 describes another magnetic pick-up for electric guitars. In the Armstrong design a polar magnet positioned longitudinally parallel to the coil and having its polar axis perpendicular to the winding axis of the coil is provided. Within the coil is either a magnet or a pole piece. The pick-up may include a plurality of coils and magnets arranged as described above to increase the effectiveness of the pick-up. Armstrong claims that this design produces a signal allowing for amplification of the natural full tones of a stringed musical instrument.
Underwood, Fender and DiMarzio, Pat. Nos. 4,269,103, 4,220,069 and 4,133,243, respectively, provide various single coil electric pick-up designs.
Clearly there are a multitude of ways of implementing an electric pick-up for an electric guitar. Other prior art that relates to the present invention is related to the assembly of the magnetic pick-ups. Zuniga Pat. No. 4,184,399 describes an assembly housed in a casing having acoustic absorptive material surrounding the major portions of the assembly, to provide acoustic isolation from the environment including mechanical vibration of the instrument itself. The assembly also includes adjusting means for varying the distance between the pick-up and all the strings simultaneously The generally rectangular casing for housing the pick-ups has a pair of leaf springs one at each end of the casing and extending transversely thereof for biasing the respective casing end away from the strings and a selectively adjustable threaded member at each end of the casing for drawing the respective casing in toward the springs. The operation of the springs on the casing provides a means for selectively adjusting the vertical position of the casing relative to the body and the frame and thereby the strings of the instrument. The frame itself is attached to the body of the electric guitar by attaching means such as screws. The adjustable threaded members at each end of the casing are also screws which attach to the casing through the frame.
Another patent which addresses the assembly of the electrical pick-up to a guitar is Stich Pat. No. 4,364,295. The Stich design is very similar to the Zuniga design; however, the leaf springs of Zuniga have been replaced by compression springs mounted on the threaded screw members. Again, the Stich design allows the spacing between the coils and the strings of the instrument to be varied by turning the threaded screw members.
From the foregoing it is apparent that there are a number of possible designs for an electromagnetic pick-up for a stringed musical instrument. All of these designs have their own advantages and sound qualities. Because of the different sound quality of each possible design, a musician may want to change the electromagnetic pick-up he is using to achieve different sound qualities for different musical pieces. To accomplish this with current state of the art, a guitarist will need to use a number of different guitars all set up with different electromagnetic pick-up systems to enable him to achieve different musical qualities for different musical pieces during the same performance. Also a guitarist today may need to change the electromagnetic pick-up of his guitar as styles change and another sound becomes more popular.
A disadvantage with today's electromagnetic pick-ups is that they are all permanently attached to the guitar by screws. Typically to install or replace a pick-up today requires the services of a professional musical instrument craftsman. Clearly, this could not be done during a performance. Thus, as described above, the guitarist must have a number of guitars with different pick-ups already installed ready for his use. This is relatively expensive.
Accordingly, there is a need for an electromagnetic pick-up for stringed instruments that can be easily installed and removed. Such an improvement in electromagnetic pick-ups will be very valuable and desirable in the field of electric guitars and other electric stringed instruments.